1. Field of the Invention
The present invention generally relates to a compressor system and, more particularly, to an improvement in a suction pipe coupling structure of a two-cylinder-type rotary compressor system having two cylinders in a sealed case.
2. Description of the Related Art
A two-cylinder-type rotary compressor having two cylinders in a sealed case has been known as a compressor used for refrigerators, air conditioners, and the like.
A two-cylinder-type rotary compressor employing such a system generally has an arrangement shown in FIG. 4 (prior art). A sealed case 2 of a rotary compressor 1 is partitioned into two portions, i.e., upper and lower portions by a stationary frame 3. A compression mechanism 4 and a motor section 5 are respectively arranged in the lower and upper portions of the sealed case 2. A stator 6 of the motor section 5 is fitted in the inner surface of the sealed case 2. A rotor 8 is rotatably supported inside the stator 6. The rotor 8 has a center axis vertically extending in the sealed case 2 and is coupled to a rotating shaft 7.
The rotating shaft 7 is supported by the stationary frame 3 with the lower end of the shaft 7 extending through a bearing portion 3a of the frame 3. Two crank portions 9 and 10 are stacked on each other together with a spacer 3b and a sub-bearing 3c at the lower end of the rotating shaft 7 extending downward from the stationary frame 3.
Cylinders 11 and 12 are respectively arranged at positions corresponding to the outer surfaces of the crank portions 9 and 10. Rollers 13 and 14 are respectively arranged in the crank portions 9 and 10 located inside the cylinders 11 and 12 so as to be eccentric with the rotating shaft 7. Blades (not shown) are in contact with the rollers 13 and 14. The blades 13a and 14a extend from the inner surfaces of the cylinders 11 and 12, respectively, so as to be freely moved backward and forward elastically. The blades partition compression chambers P1 and P2, respectively, which are defined between the rollers 13 and 14 eccentrically rotated with a phase difference of 180.degree. and the cylinders 11 and 12. That is, the volumes of the compression chambers P1 and P2 are gradually reduced, and hence a refrigerant in each chamber can be compressed.
The compressed refrigerant is discharged from a discharge pipe 2b through discharge paths (not shown).
Two suction pipes 16 and 17 are respectively connected to the cylinders 11 and 12 located at upper and lower positions as described above so as to supply the above refrigerant. The pipes 16 and 17 extend from the lower end of an accumulator 15 which is fixed to the sealed case 2 through a fixing member 2a.
The above suction pipes 16 and 17 are coupled to the accumulator 15 in advance, and are forcibly inserted in the cylinders 11 and 12 of the sealed case 2. Thereafter, the pipes 16 and 17 are externally welded to the sealed case 2, thus coupling the pipes 16 and 17 to the case 2. However, since each suction pipe has a small thickness, noise and vibration occur due to insufficient strength. In addition, in the process of attaching the suction pipes 16 and 17 coupled to the accumulator 15 to the sealed case 2 while the cylinders 11 and 12 are coupled/fixed in the sealed case 2, assembly becomes difficult.
More specifically, if there is an error such as a manufacturing error between the central distance of the cylinders 11 and 12 and that of the suction pipes 16 and 17, assembly becomes impossible. For this reason, the cylinders 11 and 12, the stationary frame 3, and the like must be selected to allow coupling positions of the respective parts to fall within a predetermined dimension range.
In brief, in a conventional, general two-cylinder-type rotary compressor, two cylinders are arranged along a rotating shaft arranged in a sealed case. One end of each suction pipe is connected to a corresponding cylinder in the radial direction. The other ends of these suction pipes extend parallel to each other, and are bent to extend along the axial direction of a rotating shaft so as to be coupled to an accumulator. The two-cylinder-type rotary compressor having the above-described arrangement is manufactured such that one end of each of the two suction pipes which are connected to the accumulator in advance is connected to a corresponding cylinder in the sealed case. With this arrangement, when the suction pipes are to be connected, the interval of the cylinders and the like must be adjusted to fall within a predetermined dimensional range, and hence processing and adjustment of parts are laborious. In addition, since the thickness of each suction pipe is small, noise and vibration tend to occur due to insufficient strength.